Shaped strips of stainless steel, stainless steel clad over aluminum, and various polymers combined with reflective metal layers are widely used as decorative trim on automobiles, trucks, boats and other vehicles. This decorative trim must be resistant to chemical attack and must have sufficient mechanical strength to resist denting after it is installed. Prior art steel and polymer based trim materials generally perform adequately but they are expensive. Accordingly, there still remains a need to provide an aluminum alloy based vehicle trim that is less expensive than steel and polymer based trim of the prior art.
The vehicle trim of our invention must be sufficiently reflective that it has substantially mirror-like characteristics, even after it is shaped in a roll-forming die or in a press. The term "substantially mirror-like" means that the trim surface has a distinctness of image ("D/I") of at least 80%. The D/I is the sharpness of a reflected image, as measured by the ratio of reflectance at 0.3.degree. from specular to the reflectance at the specular angle. That is, ##EQU1## where D/I=0 for a perfect diffuser and D/I=100% for a perfect mirror. The total reflectance of a surface is irrelevant in a consideration of its D/I.
As used herein, the term "strip" refers to a relatively narrow and thin sheet of an aluminum alloy. The width is about 1-100 cm, preferably about 2-40 cm, and the thickness is about 0.3-3.2 mm, preferably about 0.4-2.5 mm.
Numerous attempts have been made in the prior art to provide reflective metal finishes on the outer surfaces of laminated articles of various shapes for use as vehicle trim. Some prior art patents describing laminated articles having reflective surfaces are Dunning U.S. Pat. No. 4,101,698; Madonia U.S. Pat. No. 4,296,155; Nussbaum U.S. Pat. Nos. 4,349,592 and 4,368,225; Yamamoto U.S. Pat. No. 4,666,762; Yaver U.S. Pat. No. 4,877,657 and Suzuki U.S. Pat. No. 5,164,245. However, there is still a need for vehicle trim strips having a highly reflective surface, light weight and low cost.